Texas Rare Earth Resources Corp., an exploration company specializing in the heavy rare earths, is pleased to announce that it has successfully advanced the process to produce a feedstock suitable for further separation into rare earth metals.
This was accomplished by using chemical process technology that features continuous ion exchange (CIX) and continuous ion chromatography (CIC), both of which have been in use in metals and materials refining for more than 25 years.
Metallurgical work completed in 2013 demonstrated that rare earth elements (REEs) could be leached from crushed Round Top rhyolite at ambient temperature with relatively dilute sulfuric acid. The resulting leach liquids contained an appreciable amount of non-REE impurities relative to the total REEs in solution. Observed ratios of these non-REE impurities (principally aluminum, iron, and magnesium) to the REEs ranged from approximately 15 to 22:1. These impurity ratios would require a purification step to economically allow the REEs to be efficiently processed by a conventional REE processing plant due to the relatively low REE concentrations, and the high flow rates from the heap leaching operation. It was determined that a first stage of separating the REEs from the non-REEs in the PLS stream would have to be developed and was addressed in the Company's December 2013 Preliminary Economic Assessment (PEA).
In August 2014, TRER contracted with K-Technologies, Inc. (K-Tech), based in Lakeland, Florida, to conduct a study to determine the efficiency of utilizing their continuous ion exchange (CIX) technology as a method of processing the solution from the envisioned heap leach operation at Round Top. In addition, K-Tech would examine the possibility of using their continuous ion chromatography (CIC) technology to separate the individual rare earth elements from each other to produce high purity products. The work undertaken at K-Tech would be performed in three stages. The Stage 1 process would evaluate the separation of the REEs from the non-REEs in the leach solution and to produce a high concentration REE stream for further processing. Stage 2 would be to split the product stream from the Stage 1 process into three REE streams: light, mid and heavy REEs. Stage 3 would be to separate the various REEs into their individual high purity products, with focus on the production of individual purified heavy rare earth elements (HREEs).
K-Tech staff estimated that a stream with a ratio of non-REE to REE of 3:1 would be desirable to feed the Stage 2 process. The key objective for the Stage 1 testing was to assess specific CIX/CIC methodologies that would most likely be applicable to the treatment of the Round Top leach solution for the rejection of impurities from the REEs, and to produce a solution that would be a suitable feedstock for Stage 2 group REEs separation.
The testing has shown that impurity to REEs ratios in the range of 0.3:1 can be produced from solutions having initial impurity to REEs ratios in the 20 to 30:1 range. These ratios are significantly lower than the impurity to REEs ratio of 3:1 that was targeted for Stage 2 group REEs separations processing. Notably, this process removed aluminum, which comprises up to 50% of the impurities.
According to K-Tech, CIX and CIC systems potentially offer lower CAPEX and OPEX costs when compared to more traditional processes such as solvent extraction (SX). Stages 2 and 3 will be scheduled as soon as possible, along with further optimization of the work so far completed.